Abdul Khalid Ibrahim was stripped of his membership in Keadilan, also known as the People's Justice Party (PKR). Photo: AFP

One of Malaysia's main opposition parties yesterday expelled a top parliamentarian whose refusal to vacate a key post threatens to break apart the country's rising opposition alliance.

Abdul Khalid Ibrahim was stripped of his membership in Keadilan, also known as the People's Justice Party (PKR), over his refusal to vacate the post of chief minister of Selangor, Muslim-majority Malaysia's most populous state.

The affair is the worst crisis in the six-year history of the tripartite Pakatan Rakyat (People's Pact) opposition coalition, which has made historic electoral gains by offering itself as an alternative to the country's decades-old ruling regime.

Khalid's refusal to budge has been supported by key figures in the Parti Islam se-Malaysia (PAS) - a conservative Muslim party and Pakatan member - laying bare deep inter-party rivalries in the coalition.

"We have sacked him for the open defiance of party decisions and Pakatan coalition decisions," said PKR secretary general Saifuddin Nasution Ismail.

The move is likely to anger Khalid supporters within PAS. Its senior leadership was due to meet on August 17 to decide a final stand by the party.

Saifuddin said Khalid would remain chief minister of Selangor until ordered to step down by the state assembly or royalty.

National power was retained in elections last year by the long-ruling coalition dominated by the United Malays National Organisation.

Opposition leader Anwar Ibrahim has been angling to have his widely respected wife, Wan Azizah Wan Ismail, appointed Selangor boss. The move is apparently part of opposition positioning in advance of the next elections, due by 2018.

The unwieldy Pakatan features the Muslim ethnic Malay PAS, the multi-racial PKR, and the Democratic Action Party dominated by ethnic Chinese. Pakatan members have so far largely been able to paper over their considerable differences thanks to their recent electoral successes.

This article appeared in the South China Morning Post print edition as Party expels minister who won't quit